Selecting pixel color in an electronic graphic image is attained by several prior art methods. One method may be to manually select a pixel color. For example, in a software program having a trademark “Photoshop”, a group of pixels can be selected. Any color can be manually assigned to those pixels. e.g. in an RGB 48 bpp bitmap, a color red is: R=255, G=0, B=0, color white is: R=255, G=255, B=255, black is: R=0, G=0, B=0. Furthermore, in Photoshop, shadows can be created by setting a light source to particular coordinates. Shadows may have a color with low brightness. e.g. dark gray. In comparison, highlights may have a color with high brightness. e.g. bright blue or white. Highlights indicate that the light source contacts the surface. Shadows indicate that the light source does not contact the surface.
Determining whether a light source contacts a surface is a significant problem in the prior art. Prior methods are inherently limited to creating relatively simple shadows and highlights. For example, a shadow of a sphere on a flat surface. One prior art method to progromaticaly derive a pixel color may be to test a distance from particular elements in the bitmap. For example, if a pixel is less than 10 pixels from the selection, set the pixel color to dark gray.
Prior art methods essentially estimate whether a light source contacts a surface to create shadows and highlights. In the case of complex surfaces, the prior art does not calculate whether the light source contacts a particular surface. For example, in a mathematical model of planets Earth, Venus, Earths moon, and the Sun, the prior art does not calculate whether light rays from the Sun contact Earth, Earths moon, Saturn, or Venus.
In comparison, for example, the present invention calculates a location of each pixel in a complex geometric object; compares distance of points located in the same region of space; and determines whether light rays from the Sun contacts any planet. e.g. the present invention may calculate a solar eclipse of Earth on Venus at any location in their orbital path.